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Thread: Poisson distribution, university exam quistion

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    Poisson distribution, university exam quistion




    I have the following exam question witch I would appreciate some help with

    Question:
    In certain parts of a car one uses plastic plates. These plates can have cracks. The number of cracks in a plate has a Poisons distribution with mean
    Labda =0.02

    a) One inspects 50 plates. What is the probability that the number of plates with two or more cracks is larger than two?

    There are 50 plates therefore i would say 50 * labda = 1

    Probability of 2 cracks with 50 plates =
    P(x=0) + P(x=1) + P(x=2)
    for more then 2 it is 1- (P(x=0) + P(x=1) + P(x=2))

    Formula = P(X=k) = e^-labda * (labda^k / k!)

    =1-0.368-0.368-0.18=0.0842

    How to solve the part with "more than 2 cracks"
    Ore how are these related.

    Thanks in advanced

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    Re: Poisson distribution, university exam quistion


    hi,
    just think a bit about what P(x=k) means and how you include the knowledge that you are dealing with 50 plates into the formula. That would help with the first questions.

    Regarding the last one you have a probability of 1 for the event "less the 2 cracks" OR "exactly 2 cracks" OR " more then 2 cracks". if you can calculate the first two terms you can express the third.

    regards
    rogojel

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